The Thermodynamic Properties of Glassy Metals Material

Glassy metals are also referred to as an amorphous metal or a metallic glass. The formation of glass results due to rapid cooling of a metal from its molten state. In some instances, the liquid has a high viscosity and is no longer able to flow, thus forming a glassy metal. The reason for wanting to develop glassy metals is due to their wide range of properties, unlike that of crystalline materials; including magnetic, mechanical, and chemical properties. Glassy metals have also been found to exhibit good soft magnetic properties, making them even more useful. Soft magnetism refers to the materials ability to easily magnetize and demagnetize. Therefore, topics of nucleation and oxidation reactions will be very important in understand the thermodynamics behind glassy metals. Which both involve Gibbs free energy, entropy, enthalpy and heat capacities of the phase transitions. Glassy metals are expected to be high in strength and highly ductile materials, thus making them very applicable materials in medical industries, electronics, and much more. This paper will investigate the thermodynamics behind glassy metals, specifically how they are formed and the properties they exhibit. Specifically exploring the use of glass alloys in technology and medical applications, such as surgical tools.

Initially, the idea that glass was able to form was based on the classic nucleation theory. Nucleation is involved in the glass forming ability because of its importance in phase transitions. Nucleation refers to the first step in the crystallization process, in which the formation of nuclei occurs and grows to their critical sizes. There are two different types of nucleation processes, heterogenous and homogeneous. Homogenous nucleation is defined as, having large scattering due to all atoms being potential nuclei. Heterogenous nucleation is defined as, having much smaller nuclei and little variation in this. Specifically, the glass forming ability has to do with both homogenous nucleation, but the crystallization time may be influenced by both homogenous and heterogenous nucleation.

Additionally, oxidation reactions have large impacts of the behavior of metallic glasses, affecting their structure and thermostability. Oxidation is defined as a chemical reaction in which a metal and oxygen gas react to form an oxide product, such as a metal oxide and is seen as a form of corrosion. Because oxidation reactions are seen as corrosive to metals, it is normally prevented from happening in laboratories, but studies have found some positive effects of oxidation occurring on glassy metals. Typically, oxidation reactions deteriorate the glass forming ability and mechanical properties. Oxidation reactions generally occur with solid or liquid reacting with oxygen gas, forming a solid or liquid oxide.

In this experiment metallic glasses demonstrate a wide set of properties that make them very versatile materials. One of the most significant properties of glassy metals is their ability to easily magnetize and demagnetize, making them soft magnetic materials. The frequency of these soft magnetic materials. Reducing the liquidus temperature of the alloy can also be beneficial in reducing the glass transition temperature, thus increasing the glass formation ability. Additionally, the glass formation ability can be affected by the composition of the alloy. This can be looked at from two sides; the kinetic and thermodynamic. For the purpose of this exploration, we will focus on the thermodynamic effect. The glass forming ability is seen to change exponentially with composition from the eutectic point. However, ignoring the kinetic part is inaccurate because after the composition reaches the eutectic point, the kinetic factor and viscosity both may change. Moreover, amorphous metals were investigated to analyze their glass transition temperature. It has been found that increasing P in the metallic glasses can increase the thickness of amorphous alloy and increase the glass forming ability.

Due to their wide variety of properties, one of which including exhibiting soft magnetism, glassy metals have a lot of possibility in where they are being applied. Most metallic glasses can be categorized in either metallic glasses formed from transition metals (T-M) or metallic glasses alloyed from non-regular transitions metals like Fe, Co and Ni, this is the T-T type. The two most notable application of glassy metals are in technology and medical applications. Currently, glassy metals can be found in power electronics, telecommunication equipment, sensing devices, electronic article surveillance systems, and in other technological products. As mentioned previously, glassy metals are so versatile due to their extensive soft magnetism properties. Soft magnetism is defined as the ability of materials to be magnetized and de-magnetized, repeatedly. Soft magnetic materials can be found in computers, medical equipment, lighting and many more places. Due to the low frequency of the material, soft magnets in the metallic devices can be found in power transformers and electric motors.

Recently, glassy metals have had a widespread impact on the application of medical devices. Metallurgical improvement have led to enhanced biomedical and biocompatible performances in these applications. Some of the metallic glass alloys have the potential to be used as non-absorbable medical devices, while some can potentially be toxic and are avoided. Additionally, some metallic glass alloys have shown even better properties than biometals, which have been commonly used in surgical tools and load-bearing implants. Some of these properties include high strength, low elastic modulus, and a high elastic strain limit. Also, glassy metals have shown better properties than oxide glass ceramics; they are more corrosive resistant, and have higher toughness. The properties are similar to those of crystalline metals, in that they have high hardness values and wear resistance.

One medical device, glassy metals would be applicable for are surgical tools, like scalpels, with a thin metallic glass coat on a scalpel, blade sharpness and durability have been found to increase, when compared to a non-coated blade. Additionally, it has been found that the metallic glass coat prevents against microbial activity on the blade. Furthermore, glassy metals applications in cardiovascular stents are further being investigated. A cardiovascular stent is a thin device placed in the coronary arteries, to supply blood to the heart. Metallic glasses exhibit a higher elastic limit and low modulus and are higher in hardness and strength, allowing for thinner more flexible stents. The future of medical supplies is extending to use of different materials, and metallic glasses exhibit extraordinary properties that would change the world of medical supplies.

Overall, this paper investigated glassy metals, specifically the thermodynamics, properties and applications of this material in the world. It was found that glassy metals are formed through the classic nucleation theory, in which nuclei are formed to crystallize the glassy metal. Additionally, oxidation, though normally avoided, was found to have some positive impacts on the glassy metal formation. Through topics of enthalpy, entropy and Gibbs free energy, these topics were able to be better understood. Glassy metals have recently been more explored due to their highly applicable properties in many different industries. Metallic glasses are a wide growing material being used